Boldness is a key element of behavioral variation in animals. Many studies have shown variation between individuals in their propensity to take risks across a wide range of taxa, yet surprisingly few studies have investigated the importance of social context in influencing an animal's boldness. Here, we focus on the role that the sex composition of a social group plays in individual boldness in a sexually dimorphic species, the Trinidadian guppy (Poecilia reticulata). We predict that after exposure to a simulated aerial predator, male guppies should be bolder in the presence of females compared with males to maximize their mating opportunities. Furthermore, we predict that female guppies will adopt riskier behavior when shoaling with males in an effort to avoid sexual harassment. Using a model avian predator, we tested these hypotheses and found evidence to support our second prediction but not our first. Specifically, we found that male guppies returned to movement more rapidly after a fright response when shoaling with males than with females. Female focal fish in contrast returned to movement significantly quicker when shoaling with males than females. Also, we found a significant correlation in boldness across social contexts (a behavioral syndrome) in male but not female fish. This study highlights the importance of social context for individual boldness and suggests that for risk-averse behavior in social, sexually dimorphic species, sex matters.

We examined the potential of using native fish species in regulating mosquitoes in the floodplain of the Gambia River, the major source of mosquitoes

Background: Anthropogenic modification of natural habitats can create conditions in which pest species associated with humans can thrive. In order to mitigate for these changes, it is necessary to determine which aspects of human management are associated with the promotion of those pests. Anopheles gambiae, the main Africa malaria vector, often breeds in rice fields. Here the impact of the ancient practice of 'swamp rice' cultivation, on the floodplains of the Gambia River, on the production of anopheline mosquitoes was investigated. Methods: Routine surveys were carried out along 500 m transects crossing rice fields from the landward edge of the floodplains to the river during the 2006 rainy season. Aquatic invertebrates were sampled using area samplers and emergence traps and fish sampled using nets. Semi-field experiments were used to investigate whether nutrients used for swamp rice cultivation affected mosquito larval abundance. Results: At the beginning of the rainy season rice is grown on the landward edge of the floodplain; the first area to flood with fresh water and one rich in cattle dung. Later, rice plants are transplanted close to the river, the last area to dry out on the floodplain. Nearly all larval and adult stages of malaria vectors were collected 0–100 m from the landward edge of the floodplains, where immature rice plants were grown. These paddies contained stagnant freshwater with high quantities of cattle faeces. Semi-field studies demonstrated that cattle faeces nearly doubled the number of anopheline larvae compared with untreated water. Conclusion: Swamp rice cultivation creates ideal breeding sites for malaria vectors. However, only those close to the landward edge harboured vectors. These sites were productive since they were large areas of standing freshwater, rich in nutrients, protected from fish, and situated close to human habitation, where egg-laying mosquitoes from the villages had short distances to fly. The traditional practice of 'swamp rice' cultivation uses different bodies of water on the floodplains to cultivate rice during the rainy season. A consequence of this cultivation is the provizion of ideal conditions for malaria vectors to thrive. As the demand for locally-produced rice grows, increased rice farming will generate great numbers of vectors; emphasizing the need to protect local communities against malaria.